This invention relates to remote sensing devices which communicate information to a central site or another location. In particular, the present invention relates to low-powered or self-powered remote sensing devices that require no renewable or rechargeable energy source.
Many remote sensing devices include means for attachment to telephone lines to automatically dial a central site upon the occurrence of an event. An example of this is a fire alarm that is programmed to dial the fire department in case of an emergency. The event that triggers the dialing would be, for instance, a smoke detector becoming activated. The problem with many of these prior art remote sensing devices is the unknown status of their functionality while they are in use but not activated. For example, one never knows whether the smoke detector will properly dial the fire department until the happening of an event.
In addition to the above, remote sensing devices require a constant source of power to keep them monitoring and functioning. Various sources of power include the AC power lines through a direct coupling, low current draw from telephone lines and battery back up. The former two sources of power are subject to interruption while the latter is subject to exhaustion. The reliability of these power sources is therefore in question leaving the monitoring capabilities of the remote sensing device subject to failure.
The present invention overcomes these and other problems by providing for an inexhaustible power source to maintain the monitoring function in a powered-up condition at all times. The monitoring feature and perpetual timing function of the present invention is powered by removing inductively coupled AC power from long line telephone wires and storing it to power low current drain CMOS devices. The perpetual timing means and monitoring portion of the present invention is isolated from the rest of the circuit through capacitive coupling to insure that the minimum amount of current drain necessary to maintain the circuit in an active condition is available.
Three forms of the present invention are disclosed, the first being a monitoring device for a water softener or the like. This device monitors the salt requirement of the softener and calls a central site when it requires servicing. The second embodiment of the present invention discloses a monitoring device for utility meters and the like which periodically calls a central site to report the utility usage. A feature of both these embodiments, in the present invention, is the fact that these devices periodically call the central site to report their functionality. In this fashion, the central site is periodically alerted to the proper functioning of the devices. Each device contains an address which is transmitted to the central site to inform it of its location. The central site includes a computer which monitors the status of all of the outlying devices and reports to an operator when a device has failed to call in within a required window of time. The operator then can send a service person out to check on the functionality of the remote sensing device.
A third form of the present invention entails a low-powered utility sensor which communicates its data through a cabled interface to another location such as the outside wall of a customer's home. This form of a sensor requires no renewable or uninterruptable power source and can be used to read internally-installed utility meters from outside the customer's building.
Although the preferred embodiment of the present invention as disclosed herein describes a remote sensing device that removes inductively coupled AC power from telephone lines, it will be understood that this principle of the present invention applies equally well to obtaining inductively coupled AC power from any long line for use in powering a low-power remote sensing device. In addition, although the preferred embodiment of the present invention relates generally to remote sensing for utility meters, it will be understood that the principle of the invention applies equally well to remote sensing and monitoring of other types of equipment such as unattended pumps, intrusion alarms and fire alarms.